According to the ideology of the free market, Bitcoin was invented in 2008 by an unknown person known as Satoshi Nakamoto. Bitcoin began to be used as a currency in 2009, when its application was released as an open-source program. In 2021, it was adopted by El Salvador as legal tender. It is often viewed as an investment and many scholars have described it as an economic bubble. Since Bitcoin is used under pseudonyms, it has been used by criminals which has attracted the attention of regulatory authorities, leading to its ban in many countries as of 2021. Bitcoin (abbreviated as BTC; symbol: ₿) is the first decentralized cryptocurrency. It can be sent from one person to another over the Bitcoin network in a peer-to-peer manner without the need for a third party. Transactions on the network are verified using cryptography and recorded in a distributed ledger called the blockchain without a central authority overseeing it. Consensus between nodes is achieved through a resource-intensive computational process based on proof of work known as mining, which secures the Bitcoin blockchain. Mining consumes large amounts of electricity and has been criticized for the environmental impact of Bitcoin.